refactor: restructure bastion as pnpm monorepo (@lab/shared, @lab/bastion, @lab/cli)

- Split into 3 workspace packages: shared (types/constants), bastion (server), cli
- CLI binary renamed from "bastion" to "lab"
- Cross-package imports via @lab/shared and @lab/bastion workspace references
- Extracted BastionConfig, BastionState, HardwareInfo types into @lab/shared
- Added APP_NAME/APP_VERSION constants
- tsconfig.base.json with project references for build ordering
- Root workspace scripts: build, test, typecheck, clean

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bastion/src/shared/src/index.ts

@@ -0,0 +1,9 @@
+export type {
+  HardwareInfo,
+  InstallConfig,
+  InstalledInfo,
+  BastionState,
+  BastionConfig,
+} from "./types/index.js";
+
+export { APP_NAME, APP_VERSION } from "./constants/index.js";